This invention relates to a dental impression tray and has as its principal objective the provision of a new and improved dental impression tray of this general case.
Dental impression trays are now in wide use in order to produce the necessary model of the upper teeth of a patient. Such model is used by the dentist or a dental technician in the preparation of various dental devices, such as a bridge.
It has been determined that considerable care and skill is required on the part of the dentist when a hardenable material is introduced into the impression tray and the impression tray is then brought into contact with the upper teeth of a patient. This is because it is generally the practice to use a slight excess of hardenable material in the impression tray to be sure that there will be sufficient hardenable material so that a proper impression will be formed. Unfortunately the use of even a slight excess of hardenable material creates the possibility that certain of such material will flow posteriorly or will back-up into the throat of a patient. This problem is compounded because of the natural variations in the teeth disposition and spacing in various patients. Thus, it is very difficult to introduce exactly the correct amount of hardenable material into the impression tray or even to control the amount of the slight excess.
Examples of prior impression trays can be found in Osgood U.S. Pat. No. 637,480 as well as Canadian Pat. No. 950,246 and West German Pat. No. 1,952,731. In the Osgood patent there is shown a dental impression cup having a retaining wall that is fitted with an elastic body portion. However, the Osgood cup does not have any provision to allow anterior escape of excess hardenable material, as with the present invention.
It is accordingly an object of the present invention to provide an improved dental impression tray that will substantially lessen the chances of posterior escape of the hardenable material.
Yet another object of the present invention is to provide an impression tray that can be manufactured at low cost using readily available materials.